Due to restriction of physical conditions, compared with the wired link, the radio link provides a low transmission rate and a high bit error rate. When the Internet Protocol (IP) technology is applied to a wireless network cell, the packet header overhead is too high. For example, for an IPv6 speech communication packet, the packet payload really required by the user is generally 22% of the whole packet. That leads to waste of bandwidth and increases the probability of discarding the packet due to packet errors. Without effective measures, the radio network resources are wasted and the Quality of Service (QoS) is reduced.
The header compression mechanism solves the foregoing problem, and ensures inherent flexibility of the IP. Header compression mechanisms include: Robust Header Compression (ROHC) mechanism, Real-time Transport Protocol (CRTP) Header Compression mechanism, and Extended RTP (ECRTP) Header Compression mechanism.
Taking the ROHC as an example, the ROHC is a flow-based header compression solution. In the network data transmission process, most header fields in the packet of a flow have the same field value. The ROHC mechanism obtains one reference packet in a flow. For other packets, only the information about change of the header field relative to the reference packet is sent in order to accomplish compression, save the packet header overhead, and utilize the bandwidth more efficiently. Meanwhile, the ROHC mechanism controls the frequency and the quantity of feeding back messages, detects asynchronous logics, and checks errors so that the ROHC mechanism is highly effective and considerably robust. Therefore, the ROHC mechanism provides a header compression mechanism applied to the links characterized by high bit error rates and long delay.
To communicate through the ROHC mechanism in the radio network, the network needs to set up an ROHC channel. The ROHC channel is a logical channel. In this logical channel, the ingress is a compressor, and the egress is a decompressor. The compressor corresponds to the decompressor in a one-to-one relation. The compressor performs header compression for the original data, and sends the data to the decompressor through the logical channel. The ROHC channel is a unidirectional logical channel. Meanwhile, in order to support bidirectional compression, the decompressor needs to be able to feed back information to the compressor. Therefore, the ROHC feedback channel is a logical channel that bears the feedback information. The ingress is a decompressor, and the egress is a compressor.
Worldwide Interoperability for Microwave Access (WiMax) is a wireless Metropolitan Area Network (MAN) access technology based on the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard. In FIG. 1, R1 is a radio air interface, and other interfaces wired interfaces. As shown in FIG. 1, the WiMax system includes: a Mobile Station (MS)/Subscriber Station (SS), an Access Service Network (ASN), and a Connectivity Service Network (CSN). The MS/SS is a MS, through which the user accesses the WiMax network. The ASN provides radio access services for the WiMax user MS. The ASN includes a Base Station (BS) and an ASN Gateway (ASN-GW). An ASN is sharable to multiple ASNs. The CSN provides IP connection services for the WiMax user MS, for example, Location-Based Service (LBS), multimedia multicast service, broadcast service, and IP multimedia subsystem service.
However, the prior art provides no method of setting up header compression communication.